Frequently Asked Questions

Natural Hazards

The USGS monitors and conducts research on a wide range of natural hazards to help decision-makers prepare for and respond to hazard events that threaten life and property.

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USGS map displaying potential to experience damage from a natural or human-induced earthquake in 2017
No. Neither the USGS nor any other scientists have ever predicted a major earthquake. We do not know how, and we do not expect to know how any time in the foreseeable future. USGS scientists can only calculate the probability that a significant earthquake will occur in a specific area within a certain number of years. An earthquake prediction must...
Interactive Quarternary Fault Database
Many faults are mapped as individual segments across an area. These fault segments are given a different value for name, number, code, or dip direction and so in the database each segment occurs as its own unique entity. For example, the San Andreas Fault has several fault segments, from letters a to h, and fault segment 1h has segments with age...
Image: Denali Fault: Gillette Pass
This region of the United States has been tectonically active since the supercontinent Pangea broke up roughly 200 million years ago, and in large part because it is close to the western boundary of the North American plate. Since the formation of the San Andreas Fault system 25-30 million years ago, the juxtaposition of the Pacific and North...
California Aqueduct - Central Valley
The Great Valley is a basin, initially forming ~100 million years ago as a low area between the subducting ocean plate on the west (diving down under the North American plate) and the volcanoes to the east (now the Sierra Nevada mountains). Since its formation, the Great Valley has continued to be low in elevation. Starting about 20 million years...
3D perspective view of the likelihood that each region of California will experience a magnitude 6.7 within 30 years
An online map of faults that includes California can be found in the Faults section of the Earthquake Hazards Program website. Choose the Interactive Fault Map, or download KML files and GIS shapefiles from the links on the page. USGS seismic hazard maps, data and tools for California and other parts of the United States can be found in the...
1964 Alaska Earthquake damage
If you are looking for faults in California use: How Close to a Fault Do You Live? (Bay Area Earthquake Alliance) For faults in California and the rest of the United States (as well as the latest earthquakes) use the Latest Earthquakes Map: click on the "gear" icon in the upper-right corner scroll down to Map Layers, and turn on U.S. Faults mouse-...
Image shows a map of the Great Basin with fault lines shown
An online map of United States Quaternary faults (faults that have been active in the last 1.6 million years) is available via the Quaternary Fault and Fold Database. There is an interactive map application to view the faults online and a seperate database search function. KML (Google Earth-type) files and GIS shape files are also available for...
Exposed faults
A Quaternary fault is one that has been recognized at the surface and that has moved in the past 1,600,000 years, a portion of the Quaternary epoch.
Image shows an aerial view of the San Andreas Fault
Earthquakes occur on faults - strike-slip earthquakes occur on strike-slip faults, normal earthquakes occur on normal faults, and thrust earthquakes occur on thrust or reverse faults. When an earthquake occurs on one of these faults, the rock on one side of the fault slips with respect to the other. The fault surface can be vertical, horizontal,...
Fault offset along the Queen Charlotte Fault
A fault is a fracture or zone of fractures between two blocks of rock. Faults allow the blocks to move relative to each other. This movement may occur rapidly, in the form of an earthquake - or may occur slowly, in the form of creep. Faults may range in length from a few millimeters to thousands of kilometers. Most faults produce repeated...
Research has identified 17 areas in the central and eastern United States with increased rates of induced seismicity.
Earthquakes induced by human activity have been documented at many locations in the United States and in many other countries around the world. Earthquakes can be induced by a wide range of causes including impoundment of reservoirs, surface and underground mining, withdrawal of fluids and gas from the subsurface, and injection of fluids into...
Scientist pointing to graphic on a screen while children watch
Start with our Earthquake Hazards Education site. That includes: Earthquakes for Kids Cool Earthquake Facts Earthquake Science for Everyone Other good starting points include: State Geological Surveys for states in earthquake-prone regions The Great ShakeOut Earthquake Drills website IRIS (Incorporated Research Institutions for Seismology), which...